Charge cards such as credit cards, debit cards, etc. have been extensively used in various type online or arm-length transactions for exchanges of proceeds with various products or services. Many users or merchants, including those in brick and mortar stores as well as those on the go, use mobile communication devices (e.g., cell phones, tablets, laptops, etc.) paired with mobile point-of-sale terminals (e.g., credit card terminals) to conduct transactions. These charge card transactions collect signature information of the cardholders at the point-of-sale (POS) as a proof and authorization of transaction on the part of the card holder and as a part of transaction records for future dispute resolution purposes. Modern point-of-sale terminals (e.g., credit card readers on or as a part of a mobile communication device) may include touch-sensitive screen to capture cardholders' signatures entered by, for example, fingers or a writing utensil (e.g., a stylus). The mobile communication device or the point-of-sale terminal (collectively charge card transaction device hereinafter) may then package a captured signature as an image file and store or transmit for storage purposes the image file as a part of the transaction records.
To expedite the charge card payment process to increase the business flow, these charge card transaction devices oftentimes compress the image of a signature with some lossy image compression schemes to reduce the required time for transmitting the signature because the sizes of lossless images may take longer time for transmission and hence hinder the business flow. For example, an image of a signature may be packaged in a TIFF (Tagged Image File Format) container including a compressed image (e.g., a JPEG or Joint Photographic Experts Group image) to reduce the required time to transmit the captured signature image. Such conventional approaches for capturing signatures may nevertheless be subjected to various payment card fraudulent schemes such as forging signatures, duplication or skimming of charge card information, signature forgery, after-the-fact fabrication of signatures (e.g., fabrication of signatures after the transactions are completed), etc.
Therefore, there exists a need for an improved methods and systems for fingerprinting signatures and enhanced signature capturing for charge card transactions on mobile communication devices.